Lighting unit



NOV. .16 v 1926' v LIGHTING UNIT Filed Jan' 2, .1925

UNITED s-T ATI-:s lrr'rzlar-oFFlcl-LA lD. TILLSON, 0F EYANSTON,ILLINOIS.

LIGHTING UNIT.

Applicatin'led January2, 1925. Serial No. 81.

` My invention' relates to .lighting units,

particularly for use in connection with electric lamps. Itis well knowntothose familiar with the principles of indoor illumination that asemi-indirect fixture possesses great practical advantages. As the bowlsemployed are translucentthey Y revent the filament from being directlyvisible, and the transmitted' rays are dispersed in such manner as toavoldthe' productionv of sharply defined shadows A large portion of thelight emanating from the lamp is however reflected upward from the bowlto the ceiling, and these rays, together with the raysv Work isA more orless hazardous for an inexperienced person in a household and when theunits'are employed in oice buildings and the like the work addsconsiderably to the cost of general maintenance. Furthermore the possibilityof breakage is always to be considered. The general object ofmy invention isto produce a semi-direct lighting unit which will have ahigh degree of efiiciency and will at the same time prevent-the`admission of dust. One of the contributory objects of the inventionis to provide a unit having a flattened translucent lower portion. As aresult of this Va substantial portion of the lightv is reflected upwardtoward the ceiling instead of being too widely distributed laterally.-Another object is to obtain a unifprm lflux up through the top of thefixture to thereby prevent uneven illumination of the ceiling. furtherobject is to provide a unit through which lamps of the larger sizes may.readily pass and which will at the same time reduce to a minimum theshadows resulting from the presence of the means by' which theindividual elements of the units are held to'- rlgether. Another .objectis to provide a construction in". whichl the suspending elements bywhich the canopy supports the transparent and translucent elements maybe concealed, thus improving the appearance of' the fixture. Anotherobject is to provide means for masking the inequalities in the inensityofthe light at dierent parts of the xture.

I accomplish my objects by the mecha.

nism illustrated in the accompanyingdrawings in whichi Figure l is aside elevation of the complete unit showing its external appearance.

Figure 2 is a side elevation of the unit chiefly in central section.

Figure 3 is a bottomfplan section on the line 3 3 Figure 1. y

Like numerals denote like parts throughout the several views.

In theform selected to illustrate the in'- vention the hollow body 1 isof gla, formed being a flattened body 'of revolution sym'- metricalabout its central vertical axis and having its median zone about midheight. Thebody has a central opening 2 at the top which in theillustrated form is of a diameter less .than half the maximum diameterof the unit. At the rim of this central openving is a flange 3 which isexternally channeled to receive the inner end of set screws 4 by whichthe said ported.

Below the'median zone the glass is translucent, that is, capable oftransmitting a portion of the light rays and also of reiecting a portionof them. This condition may be obtained in different ways, forexalnple,by providing a heavy coat of fired-on enamel. The portion -above themedian zone is approximately transparent, but by preference is notentirely so lhaving a light coat of fired-on enamel in order that thelight rays or lumins passing through may be somewhat dispersed ,toprevent the formaftion of a direct image of the filament on the ceilingor other reflecting surface above.

Inthe preferred form there is a portlon 6 at the bottom of the bodywhich is shal- ,in a single piece, and is of lenticular shape,

gl-ass body is sup- D lowly 4(lished for the purpose of reflecting therays almost vertically upward.v The diameter of this portion is hereshown to be approximately three-.quarters of the maximum diameter of thefixture.y The portion above the median zone is curved-in the illustratedform being flatly arched, sothat the light rays will pass throughwithout excessive lateral distribution.

As the body is shallow the lamp 8 approaches rather closely to thebottom, which tends to produce a spot of increased brilliance at thecentral bottom port-ion. To mask this it is desirable to form aSunburstv 10 at the lower central area.

The lampsocket 14 is enclosed within 'a cap 16 which is preferablytruste-conical in genera-l appearance. At the lower rim of the cap is -areducing ring 18 which is of glass which is approximately transparentlike `the upper portion of the main body. This forms part of the closureat the upper part of the body and permits the rays from the filament topass up through it. A connector ring 2() has an internal flange 22 whichrests upon the reducing ring. It also has a depending flange 24 whichcircumferentially sunrrounds but is spaced slightly from the flange 3 ofthe body 1. This connector rings among other things forms a housing ordust guard which tends to shed the dust and at the" same time affords apassage for air as the latter expands and contracts due to the heatingand cooling of the lamp when the latter is turned on and off.

While the glass parts may he supported -in `different ways from cap` 16l have shown an advantageous one in which there are three straps 26,which pass up to the inside of the cap and are there fastened by setcrews 28. lihese strap-s pass down along the inside of the reducing ring18 and are secured to the inside of the connector ring 24 by the setscrews 4 previously mentioned. These screw into the lower end of thestraps and project into the channeled rim 3 of the body 1 and thus holdthe parts assembled.

As a result of my invention have produced a lighting unit which has theadvan- 1 tages of the ordinary semi-indirect open f bowl unit with ltheadded advantage of being closed at the top so as to exclude dust. rll`heelements which form the closure at the top of the unit are a simple formand at the same time permit the air flow resulting from the alternateheating and cooling of' the lamp.

' The unit is of attractive appearance andv may be used in connection,with any standard form of socket and lamp.

Having thus described my invention what l claim as new `and desire tosecure by Letters Patent is:

1. An inclosed lighting fixture having a hollow glass globe with acentral opening at the top,a cap of less maximum diameter than saidopening and located above the globe, a plurality of straps having theirup.- per ends secured to the cap and extending downwardly and outwardlywith their lower ends disposed in overlying relationrin respeot to theouter face of the upper end of the globe, a fastening element carried bythe lower end of each strap and engaging in a groove in the globe, and atransparent closure between ,the cap and globe supported. on saidstraps, and having an upwardly extending flange disposed between thestraps and cap.y

2. An inclosed lighting fixture having a hollow glass globe with acentral openingat the top, a cap of less maximum diameter than saidopening and located above the globe, a plurality of straps having theirupper ends secured to the cap and extending outwardly and downwardlywith their lower ends disposed in overlying relation to the outer faceof the'upper end of the globe, a fastening element carried by the lowerend of each strap engaging in a groove in the globe, a transparentclosure between the cap and globe supported on said straps, a dustexcluding ring surrounding the upper end of the globe and through whichsaid fastening elements extend, and a flange on the upper end of saidring rengaging upon the upper surface of said closure.

3. An inclosed lighting fixture having a hollow glass globe with acentral opening at the top, a cap of less maximum diameter than saidopening and` located above the globe, a plurality of straps having theirupper ends secured to the'cap and extending downwardly and outwardlywith their lower ends disposed in overlying relation in respect to theouter face of the upper end of the globe, a fastening element carried bythe lower end of each strap and engaging in a groove in the globe, atransparent closure between the cap and globe supported on said strapsand having an upwardly extending flange disposed between the straps andcap,'

a dust excluding ring surrounding the upper end of the globe and throughwhich said fastening elements extend, and a Hange on the upper end ofsaid ring engaging upon the upper surface of said closure. v

lin witnesswhereof, l' have hereunto subscribed myv name.

EDVIN D. TILLSON.

